Rain is due tomorrow in the southeast and along the southern Black Sea coast, while the rest of Bulgaria stays mostly sunny.
Skies will be mostly clear overnight. There will be almost no wind in western and central Bulgaria, but a light to moderate north wind will blow across the eastern half of the country. Frost is likely by morning in low-lying areas of western and central Bulgaria. Lows will dip to 2-4C in the valleys and climb to 11-13C in the east, with Sofia around 5C. Air pressure stays above the monthly average and won't change much.
Tomorrow afternoon, mid- and high-level clouds will move in, thickening in the southeast, where rain is expected. Winds will blow moderate from the northeast, picking up to strong in eastern Bulgaria. Highs will reach 18-23C, with Sofia around 18C.
Along the Black Sea coast, the day will stay mostly sunny too, though clouds will build up for a while in the afternoon, mainly along the southern coast, where rain is expected. Temperatures there will hit 18-20C. The sea will be 20-21C, with waves of 3-4 on the sea-state scale.
In the mountains, skies will stay mostly sunny, with some clouds rolling in during the afternoon but no rain, and a strong northeast wind. At 1,200 metres, expect around 12C; at 2,000 metres, around 5C.
On Saturday, most of Bulgaria will see sunshine, with more cloud over the eastern regions. Light rain will fall only in isolated spots in the far southeast. Winds will be light, turning moderate to strong from the north-northeast along the coast, and frost will return to the valleys of western and central Bulgaria. Temperatures will range from 5-10C at night to 18-23C by day.
Sunday will be mostly sunny, though low cloud and some fog will linger over eastern Bulgaria in the morning. Winds will ease off, dying down completely in many areas, and daytime temperatures will edge up slightly.